Can you use a reverse osmosis filters and tankless heaters together?

Depending on where you live, you might have a less than ideal source of water. If you have poor water quality where you live, you might turn to a system like a countertop water filtration system or a reverse osmosis filter system to provide clean and pure water to your whole house.

You may ask yourself, does it make sense to use RO water in your tankless water heater?

Impact of Reverse Osmosis

A few things to consider with reverse osmosis – first of all it lowers the pH value of the water. This will impact the taste of the water, but not how it will interact with the tankless water heater. The most important factor is that reverse osmosis removes up to 99% of all the sediments in your water, with the innovative membrane the filter uses.

That means the most dreaded part of owning a tankless water heater — performing annual maintenance — will virtually be gone if the water has been treated with reverse osmosis. The majority of the maintenance required with a tankless water heater is because the water has too much sediment which builds up around the heat exchanger, such as calcium and limescale. However, these sediments will be filtered out by the reverse osmosis membrane and never actually make it into the tankless water heater. Therefore, you will have to do significantly less, if not any, maintenance on your tankless water heater.

Water waste – don’t let it in your system!

The one problem you may run into is that reverse osmosis, as it currently stands, tends to waste water in order to filter it. This is because a significant amount of water is required to flush all that sediment out of the RO membrane. That means you might need a more advanced setup to ensure that the flush water doesn’t get into the tankless water heater; which could cause significant damage.

Installation – don’t do it yourself!

Make sure you contact a local plumbing professional to install an RO / Tankless water heater setup. Because you are either working with live electricity lines, or even more dangerous, natural gas lines, you should definitely be working with a certified professional. We do not recommend a do it yourself (DIY) approach to tankless water heating, it can be quite dangerous, and expensive if you make a mistake. It’s worth noting that most of the brands will void the warranty if you cannot prove that it was installed by a certified professional in your area.

Bottom Line – it can be done

Yes, you can use an RO system together with a tankless water heater and expect that you will have significantly less maintenance to perform on your heating unit. That said, be prepared for increased water costs, as the RO membrane will require significant amounts of water to flush out all the sediments that aren’t making their way into your tankless water heater.

Our top Picks in Tankless Water Heaters

We’ve all heard that switching from a hot water tank to a tankless water heater will save you money on energy costs over time. Of course, these cost savings usually come with a lot of up-front cost. Thankfully, we’ve reviewed the best tankless water heaters in terms of price, that are still of high quality yet won’t break the bank. In fact, they will pad the bank over time. We hope that our list will help you make a successful upgrade to a tankless water heater without blasting money on the premium brands.

Best Value – Takagi Tankless Water Heater

Takagi Tankless Water HeaterTakagi makes the most powerful tankless water heaters for the most affordable prices. In fact, their flow rate, in terms of GPM, often exceeds the competitive models from Rheem and Rinnai. This Takagi model boasts a massive 10 GPM, which for some context is able to power up to 3 full flow shower heads at the same time. If taking 3 showers isn’t required, you can also take a shower, run your dishwaster and run your washing machine, all without ever running out of hot water! Backed by both an industry leading warranty and hundreds of positive reviews, we think going with the Takagi is a great choice for you.

Best Price – Titan Electric Water Heater

If you aren’t up for buying a huge natural gas unit from Takagi with 10 GPM, you can get yourself a much cheaper tankless water heater in the Titan Electric Tankless. Another mostly unkonwn brand, it is backed also by a huge base of positive reviews on amazon as well as an industry leading warranty. As with many “unknown brands”, they have higher flow rates for a cheaper price than the premium brand models, even if the quality appears to be the same. The draw back is that this unit is not very visually appealing, but if it’s tucked away out of sight, who cares? We highly recommend the Titan Electric Water Heater to anyone who has modest GPM needs and is looking for the electric tankless water heater.

Best in Outdoor – Rheem Outdoor Tankless Water Heater

Rheem outdoor tankless water heaterWhile Rheem is known for being a premium brand, we are surprised to see how affordable and how high quality their outdoor tankless water heaters are. In fact, we find that the outdoor models are somehow cheaper than the the indoor tankless heaters. How this came to be, we’re not sure, but as a consumer we welcome it. According to the iWP Foundation, The Rheem outdoor tankless water heater boasts 7.5 GPM, 96% efficiency and thermally rated for temperatures of -30F, which is good enough for most homes across Canada and The United States. If it’s outdoor tankless water heaters you seek, and a limited budget, you can always count of the quality and customer support of Rheem.